The ability of enzymes to catalyze biological reactions is fundamental to life. A range of biological applications use enzymes to synthesize various biomolecules in vitro. One particularly useful class of enzymes are the polymerases, which can catalyze the polymerization of biomolecules (e.g., nucleotides or amino acids) into biopolymers (e.g., nucleic acids or peptides). For example, polymerases that can polymerize nucleotides into nucleic acids, particularly in a template-dependent fashion, are useful in recombinant DNA technology and nucleic acid sequencing applications. Many nucleic acid sequencing methods monitor nucleotide incorporations during in vitro template-dependent replication of a target nucleic acid molecule by a polymerase.
When using an enzyme to catalyze a biological reaction of interest, it can be useful to confine the enzyme so that it is co-localized with its substrate. Such co-localization can increase the rate or efficiency of enzymatic catalysis, thereby increasing the enzymatic activity and/or product yield under a given set of reaction conditions. Various methods of co-localizing enzymes with substrates, typically by immobilizing the enzyme on a support that is then contacted with a solution including the substrate, have been reported. However, such methods typically cause a reduction in enzyme activity and succeed only at low efficiencies. Such methods typically also require modification of the enzyme prior to or after enzyme immobilization, which can be time-consuming and technically challenging to perform. There remains a need in the art for simple, efficient and reliable methods to tether enzymes to, or in the vicinity of, their target substrates so as to increase the rate or product yield of the enzymatic reaction, as well as more generally to tether proteins to desired locations.